Also need to remember that P2 and P3 are recruited differently.
P2 was always (and still is a selection). OASC, and CBAT if reqd, then the top scorers selected. P3 was a race to "jump through the necessary hoops". Applicants were loaded onto courses on completion of the "hoops" then the trade would shut. There never really has been selection for P3, more a minimum standard. If you pass the minimum standard (AST, SI) then it is a race. No selection takes place after the AST and SI.
Edit: Beaten to this point by ATG by 3 minutes.